Stent coating device

ABSTRACT

The present invention is a method and device, which is suitable for use in an operating theater just prior to implantation, for selectively applying a medical coating to an implantable medical device, for example a stent. Disclosed is a device for use with a stent deployed on a catheter balloon. The device is configured to apply a medical coating of a desired thickness to the surface of a stent only. This is done by use of a drop-on-demand inkjet printing system in association with an optical scanning device. The device is further configured so as to, if necessary, apply a plurality of layered coats, each layered coat being of a different coating material, and if appropriate, different thickness. The section of the housing in which the stent is held during the coating procedure is detachable from the housing base. The detachable housing section may be easily cleaned and re-sterilized or simply disposed or simply disposed of.

[0001] This is a continuation-in-part of U.S. patent application Ser.No. 10/136,295, filed on May 2, 2002.

FIELD OF THE INVENTION

[0002] The present invention relates to coating medical devices intendedfor in vivo deployment and, in particular, a method and device suitablefor use in an operating theater just prior to implantation, forselectively applying a medical coating to an implantable medical device,for example a stent.

DEFINITIONS

[0003] The term “prosthesis” refers to any one of many medical coatingapplications including but not limited to coronary stents, peripheralvascular stents; abdominal aortic aneurysm (AAA) devices, biliary stentsand catheters, TIPS catheters and stents, vena cava filters, vascularfilters and distal support devices and emboli filter/entrapment aids,vascular grafts and stent grafts, gastro enteral tubes/stents, gastraenteral and vascular anastomotic devices, urinary catheters and stents,surgical and wound drainings, radioactive needles and other indwellingmetal implants, bronchial tubes and stents, vascular coils, vascularprotection devices, tissue and mechanical prosthetic heart valves andrings, arterial-venous shunts, AV access grafts, surgical tampons,dental implants, CSF shunts, pacemaker electrodes and leads, suturematerial, wound healing, tissue closure devices including wires,staplers, surgical clips etc., IUDs and associated pregnancy controldevices, ocular implants, timponoplasty implants, hearing aids includingcochlear implants, implantable pumps (like insulin pumps), implantablecameras and other diagnostic devices, drug delivery capsules, leftventricular assist devices (LVADs) and other implantable heart supportand vascular systems, indwelling vascular access catheters andassociated devices (like ports), maxilo fascial implants, orthopedicimplants (joint replacement, trauma management and spine surgerydevices), implantable devices for plastic and cosmetic surgery,implantable meshes (such as for hernia or for uro-vaginal repair, braindisorders, and gastrointestinal ailments).

[0004] The term “drop-on-demand” refers to any active or passive releaseof a predetermined drop or number of drops equivalent to a desiredquantity of coating material. Drop-on-demand also refers to jetting whena sequence of drops is released. One example of “drop-on-demand” is thepiezo drop-on-demand technology such as that manufactured by Ink JetTechnology, Inc. of San Jose, Calif. which provides applicators for awide variety of coating applications. Such micro-machined ceramicdesigns are robust and chemically inert to almost every kind of fluidand coating and are compatible with a wide range of fluids with extremepH values or strong solvent characteristics. Non-Newtonian fluids arealso compatible with such devices due to the internal design of theapplicator allowing laminar flow of the fluid. With a built in heaterand high temperature operating potential, piezo drop-on-demandapplicators are compatible with a wide variety of coating materials.

[0005] The term “detector” or “detecting” refers to any device or methodwhich uses energy, such as magnetic, electrical, heat, light, etc. todetermine whether a target at a desired location on the prosthesis hasbeen located and signals the applicator to drop-on-demand or marks thelocation as one to be coated. The detector does not determine thelocation of the applicator relative to the target to provide feedbackfor positioning the applicator. The detector determines the points onthe coordinate table for desired locations on the prosthesis byproviding signals for the applicator controller that are immediatelyused or stored as coordinate tables. Examples of detectors are lightsensitive devices such as CCD area cameras, CCD line cameras,high-resolution CMOS area cameras, or devices that can capture lightreflected or transmitted by the prosthesis, and electrically sensitivedevices such as capacitance detectors.

[0006] The term “applicator” or “applying” refers to any configuration,apparatus, or method for positioning a coating material to a surfacefrom a reservoir such as a point source including but not limited to anozzle, a dispenser, or tip, or a multipoint source. An example of anapplicator is a drop-on-demand ink-jet.

[0007] The term “on-the-fly” refers to translation and drop-on-demanddelivery that is synchronous or close to synchronous, and/orsimultaneous or close to simultaneous. Unlike freestyle movement whichrequires stopping for validation of preceding and subsequent movementwith relation to the prosthesis, on-the-fly continues to next movementwithout validation step. FIG. 13 illustrates an example of on-the-flydrop-on-demand with an embodiment where the axis of rotation 700 isstationery and applicator is moving in the Z axis. A servo controller705 directs the Z drive 710 which is coupled to applicator 725 whilemonitoring the velocity and location of the applicator 725 via feedbackdevice 715. The servo controller 705 keeps the Z drive 710 withinpredetermined limits of the required velocity and signals the applicatorcontroller 720 to activate the drop-on-demand applicator using data fromfeedback device 715 with reference to coordinates from the pre-scan by adetector determining points to be coated. In this procedure thevalidation of the Z position of the applicator 725 is done in real-timeby the servo controller 705. The servo controller 705 interacts with theaxis of rotation to determine the next location based on the lastlocation and the time which it takes Z drive 710 to move applicator 725to the next location. Feedback device 715 provides feedback that is aninternal servo-based logic procedure and is not connected to the actuallocation relative to the prosthesis and therefore does not become avalidation step as discussed above. In alternative embodiments, theservo controller 705, Z drive 710, Z location feedback device 715, theapplicator controller 720, and the applicator 725 can be all be bundledinto the application control module (not shown).

[0008] The term “freestyle” refers to movement of an applicator over aportion of a prosthesis to be coated that requires validation through apredetermined user selected pattern and/or a feedback loop of applicatorposition relative to the portion of the prosthesis to be coated.Validation is done prior to delivery of the coating material. In oneembodiment, freestyle movement moves the applicator over a predeterminedposition based on a user selected pattern. The position of theapplicator is verified relative to the prosthesis and a new location iscalculated. The applicator is moved to a new and more accurate location.The applicator delivers the coating material and then moves to the nextpredetermined location based on the user selected pattern.

[0009] It is noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless expressly and unequivocally limited to one referent. Thus forexample, reference to “an applicator” includes two or more applicators,but “n is an integer from 1 to 60” means that n is one integer becausethat is limited to one integer. Also noted that as used herein, the term“polymer” is meant to refer to oligomers, homopolymers, and copolymers.The term “therapeutic agent” is meant to refer to drugs, therapeuticmaterials, diagnostic materials, inerts, active ingredients, andinactive ingredients.

[0010] For the purposes of this specification and appended claims,unless otherwise indicated, all numbers expressing quantities ofingredients or percentages or proportions of other materials, reactionconditions, and so forth used in the specification and claims are to beunderstood as being modified in all instances by the term “about.”Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending upon the desired propertiessought to be obtained by the present invention. At the very least, andnot as an attempt to limit the application of the doctrine ofequivalents to the scope of the claims, each numerical parameter shouldat least be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques.

[0011] Notwithstanding that the numerical ranges and parameters settingforth the broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Moreover, all ranges disclosed hereinare to be understood to encompass any and all subranges subsumedtherein. For example, a range of “1 to 10” includes any and allsubranges between (and including) the minimum value of 1 and the maximumvalue of 10, that is, any and all subranges having a minimum value ofequal to or greater than 1 and a maximum value of equal to or less than10, e.g., 5.5 to 10.

BACKGROUND OF THE INVENTION

[0012] The practice of coating implantable medical devices with asynthetic or biological active or inactive agent is known. Numerousprocesses have been proposed for the application of such a coating.Soaking or dipping the implantable device in a bath of liquid medicationis suggested by U.S. Pat. No. 5,922,393 to Jayaraman, soaking in anagitated bath, U.S. Pat. No. 6,129,658 to Delfino et al. Devicesintroducing heat and/or ultrasonic energy in conjunction with themedicated bath are disclosed in U.S. Pat. Nos. 5,891,507 to Jayaramanand 6,245,4 BI to Alt. The device of U.S. Pat. No. 6,214,1 BI to Tayloret al. suggest spraying the medication by way of pressurized nozzles.

[0013] Initially such coating were applied at the time of manufacture.For various reasons such as the short shelf life of some drugs combinedwith the time span from manufacture to implantation and the possibledecision of the medical staff involved concerning the specific drug anddosage to be used based on the patient's at the time of implantation, aneed has arisen for technologies which permit applying a coating justprior to implantation. Wrapping the implantable device with medicatedconformal film is disclosed in U.S. Pat. No. 6,309,380 BI to Larson etal. Dipping or soaking in a medicated bath just prior to implantationare suggested in U.S. Pat. Nos. 5,871,436 to Eury, 6,6,454 to Berg etal., and 6,1171,232 BI to Papandreou et al. U.S. Pat. No. 6,3,551 BI toWu provides a bathing chamber for use with specific implantable devicesuch as the stent deployed on the balloon of a catheter (FIG. 1).

[0014] Each of the methods and devices intended for use just prior toimplantation, listed above, deposit the coating material onto any andall surfaces that are exposed to the coating. This may result indepositing coating material on surfaces on which the coating is unwantedor undesirable. Further, the coating may crack or break away when theimplantable is removed from the implantation apparatus. An example ofthis would be a stent deployed on a catheter balloon. As the balloon isinflated and the stent is expanded into position, the coating may crackalong the interface between the stent and the balloon. These cracks maylead to a breaking away of a portion of the coating from the stentitself. Similar problems can occur in cases where the coating techniquefails to prevent inadvertent overlapping with the edges (e.g., internalsurfaces along the edges) of various devices (e.g., struts of stents).This, in turn, may affect the medicinal effectiveness of the coating,and negatively affect the entire medical procedure.

[0015] It is known to use Ink-Jet technology to apply a liquid toselected portion of a surface. In the paper “Applications of Ink-JetPrinting Technology to BioMEMS and Microfluidic Systems,” presented atthe SPIC Conference on Microfluidics and BioMEMS, October, 01, theauthors, Patrick Cooley, David Wallace, and Bogdan Antohe provide afairly detailed description of Ink-Jet technology and the range of itsmedically related applications(http://www.microfab.compapers/papers_pdf/spie biomems_O1_reprint.pdf).

[0016] A related device is disclosed in U.S. Pat. No. 6,001,311 toBrennan, which uses a moveable two-dimensional array of nozzles todeposit a plurality of different liquid reagents into receivingchambers. In the presentation of Cooley and the device of Brennan, theselective application of the material is based on an objectivepredetermined location of deposit rather that on a “subjectiveplacement” as needed to meet the requirements of a specific applicationprocedure. With regard to the application of coatings applied to medicaldevices with inkjet applicators, while it is possible to coat only achosen portion of a device, such as only the stent mounted on acatheter, but not the catheter itself. This type of procedure usingcurrent technologies may, however, require providing complex data files,such as a CAD image of the device to be coated, and insuring that thedevice be installed in the coating apparatus in a precise manner so asto be oriented exactly the same as the CAD image.

[0017] Other systems which use ink-jet applicators apply the coatingwith a “freestyle” procedure. The freestyle points are determined by apreprogrammed user selected pattern that is unique to the particularshape or contour for the type of prosthesis and the desired coating tobe achieved, much like a vector based printing approach. The ink-jetnozzle or prosthesis move in three-dimensionally with the aid of amotion control system. The motion control system enables the ink-jetnozzle to move over the portions of the prosthesis to be sprayed.Alternatively, a real-time picture can be taken with a camera todetermine the position of the ink-jet nozzle in relation to theprosthesis. Based upon the feedback of nozzle location, the ink-jetapplicator can be controlled by activating the spray, moving the ink-jetnozzle, and/or moving the prosthesis to adjust to the pattern to betterconform with the actual prosthesis.

[0018] This type of system is particularly inefficient because thepreprogrammed user selected pattern fails to accommodate inherentvariability in the surface of the prosthesis. In one non-limitingembodiment, for example, a stent crimped around a balloon catheter willnot be crimped such that it has the same surface each time. The crimpingcannot be determined from the factory according to the manufacturer'sspecifications of the stent. Further, using this type of feedback loopserves merely as a “first impression” to control the spraying, nozzleposition, and/or prosthesis position, and freestyle systems consequentlyincrease the time required to apply the coating. In the operationaltheatre, this is undesired because many types of coatings (e.g.,paclitaxel, rapamycin, or several other pharmaceutical compounds orbioactive agents) have to be applied to the stent crimped on the ballooncatheter immediately prior to surgery.

[0019] The significance of delivering drug-loaded prostheses may offersavings benefit in time and cost. Studies have been conducted to showthe importance of delivering the correct drug dose density on coronarystents to prevent restenosis by application of paclitaxel or rapamycin.Kandazari, David E. et al., Highlights from American Heart AssociationAnnual Scientific Sessions 2001: Nov. 11 to 14, 2001, American HeartJournal 143 (2), 217-228, 2002; Hiatt, Bonnie L. et al., Drug-ElutingStents for Prevention of Restenosis: In Quest for the Holy Grail,Catheterization and Cardiovascular Interventions 55:409-417, 2002;Kalinowski, M. et al., Paclitaxel Inhibits Proliferation Of Cell LinesResponsible For Metal Stent Obstruction: Possible Topical Application InMalignant Bile Duct Obstructions, Investigational Radiology37(7):399-404, 2002. Other studies have shown how accuracy of doserelated to cytotoxicity of coating drugs. Liebmann, J. E. et al.,Cytotoxic Studies Of Paclitaxel (Taxol) In Human Tumor Cell Lines, Br.J. Cancer, 68(6):1104-9, 1993; Adler, L. M. et al., Analysis Of ExposureTimes And Dose Escalation Of Paclitaxel In Ovarian Cancer Cell Lines,Cancer, 74(7):1891-8, 1994; Regar, E. et al., Stent Development AndLocal Drug Delivery, Br. Med. Bulletin, 59:227-48, 2001. See alsohttp://www.tctmd.com/expert-presentations: Farb, A., ComparativePathology Of Drug Eluting Stents: Insights Into Effectiveness AndToxicity From Animal Lab, CRF Drug-Eluting Stent Symposium 2002; Grube,E., Taxol-Eluting Stent Trials, ISET 2002 Miami Beach, Mar. 19-23, 2002(The effect of taxol on the edges of the stent and dose responsescreening); Carter, Andrew J., Sirolimus: Pre-ClinicalStudies—Evaluation Of Dosing, Efficacy And Toxicity, TCT September 2001.

[0020] There is therefore a need for a device, and method for its use,whereby a coating is selectively applied to an implantable medicaldevice just prior to implantation, such that only the device or selectedportions thereof are coated. It would be desirable for the device toprovide for user selection of coating material and dosage to be applied,thereby providing choices as to the specific coating material and dosageto be applied based on the specific needs of the patient at the time ofimplantation. It would be further desirable for the device to provide asterile environment in which the coating is applied and the device issuitable for use in an operating theater.

[0021] Finally, a method and apparatus for coating a prosthesis isdesired that will reduce the time of coating by coating the prosthesis“on the fly” without having to stop at each point to apply the coating.

SUMMARY OF THE INVENTION

[0022] The present invention is a method and device, which is suitablefor use in an operating theater just prior to implantation, forselectively applying a medical coating to an implantable medical device,for example a stent.

[0023] According to the teachings of the present invention there isprovided, a coating device for selectively applying a coating tosurfaces of an object, the device applying the coating based uponoptical properties of the surfaces such that the coating is applied tosurfaces of a first type and is not applied to surfaces of a secondtype, the first type of surface being optically distinguishable from thesecond type of surface, the coating device comprising: at least oneobject-holding element configured to hold the object while a coating isapplied; at least one optical scanning device deployed so as to scan atleast a portion of the object, the optical scanning device configured soas to produce output indicative of the types of surfaces of the object;at least one coating applicator deployed so as to deposit a fluid so asto coat at least a portion of the object; at least one fluid deliverysystem in fluid communication so as to supply the fluid to the coatingapplicator; a processing unit being responsive at least to the output soas to selectively activate the coating applicator, thereby applying thecoating substantially only to surfaces of the first type; and a drivesystem configured so as to provide relative motion between the surfaceof the object and the coating applicator, and between the surface of theobject and the optical scanning device.

[0024] According to a further teaching of the present invention, thedrive system is configured so as to rotate the object-holding elementabout an axis perpendicular to a direction of application of the coatingapplicator.

[0025] According to a further teaching of the present invention, the atleast one object-holding element is implemented as two object-holdingelements configured so as to simultaneously support the object at twodifferent regions along a length of the object.

[0026] According to a further teaching of the present invention, the twoobject holding elements are mechanically linked so as to rotatesynchronously about a single axis, the axis being perpendicular to adirection of application of the coating applicator.

[0027] According to a further teaching of the present invention, the atleast one coating applicator includes a pressure-pulse actuateddrop-ejection system with at least one nozzle.

[0028] According to a further teaching of the present invention, aspatial relationship between the coating applicator and the object isvariable.

[0029] According to a further teaching of the present invention, thespatial relationship is varied along a first axis that is parallel to adirection of application of the coating applicator, and a second axisthat is perpendicular to the direction of application of the coatingapplicator.

[0030] According to a further teaching of the present invention, thecoating applicator is displaceable relative to the object-holdingelement, the displacement being along the first axis and the secondaxis, thereby varying the spatial relationship.

[0031] According to a further teaching of the present invention, boththe coating applicator and the optical scanning device are deployed on adisplaceable applicator base, displaceable relative to theobject-holding element, the displacement being along the first axis andthe second axis, thereby varying the spatial relationship.

[0032] According to a further teaching of the present invention, the atleast one coating applicator is implemented as a plurality of coatingapplicators and the at least one fluid delivery system is implemented asan equal number of fluid delivery systems, each fluid delivery systemsupplying a different fluid coating material to the coating applicatorwith which the each fluid delivery system is in fluid communication.

[0033] According to a further teaching of the present invention, theobject is a catheter that includes a balloon portion on which a stent isdeployed, such that the stent is a surface of the first type and theballoon is a surface of the second type surface.

[0034] According to a further teaching of the present invention, theprocessing unit is responsive to an indication of the relative motion soas to change operational parameters of the coating device as required.

[0035] According to a further teaching of the present invention, theobject-holding element, the coating applicator, the optical scanningdevice, the drive system and at least a portion of the fluid deliverysystem are deployed within a housing that includes an applicationcompartment.

[0036] According to a further teaching of the present invention, thehousing includes a base housing section and a detachable housingsection.

[0037] According to a further teaching of the present invention, theapplication compartment is defined by portions of both the base housingsection and the detachable housing section.

[0038] According to a further teaching of the present invention, thebase housing section includes the coating applicator, at least a portionof the fluid delivery system, the optical scanning device and theprocessing unit and at least a first portion of the drive system, andthe detachable housing section includes the object-holding element andat least a second portion of the drive system.

[0039] According to a further teaching of the present invention, thebase housing section includes at least one fluid delivery system.

[0040] According to a further teaching of the present invention, thedetachable housing section is disposable.

[0041] According to a further teaching of the present invention, theapplication compartment is a substantially sterile environment.

[0042] According to a further teaching of the present invention, thecoating applicator, and the fluid delivery system are included in aremovable sub housing, the removable sub-housing being deployed with inthe application compartment and the removable housing being detachablyconnected to the processing unit.

[0043] There is also provided according to the teachings of the presentinvention, a coating device for selectively applying a coating tosurfaces of an object, the device applying the coating based uponoptical properties of the surfaces such that the coating is applied tosurfaces of a first type and is not applied to surfaces of a secondtype, the first type of surface being optically distinguishable from thesecond type of surface, the coating device comprising: a) a housingwhich includes an application compartment; b) at least one objectholding element deployed within the application compartment, the objectholding element configured to hold the object to which a coating isapplied; c) a displaceable applicator base deployed within theapplication compartment, the applicator base including: i) at least onecoating applicator aligned so as to deposit a fluid whereby at least aportion of the object is coated; and ii) at least one optical scanningdevice deployed so as to scan at least a portion of the object, theoptical scanning device configured so as to produce scanning outputindicative of the different types of surfaces of the object, thedisplacement of the applicator base resulting in a variance of a spatialrelationship between the coating applicator base and the object; d) atleast one fluid delivery system in fluid communication so as to supplythe fluid to the coating applicator; e) a processing unit beingresponsive at least to the output so as to selectively activate thecoating applicator, thereby applying the coating substantially only tosurfaces of the first type; and f) a drive system configured so as toprovide relative motion between the surface of the object and theapplicator base.

[0044] According to a further teaching of the present invention, thehousing includes a base housing section and a detachable housingsection.

[0045] According to a further teaching of the present invention, theapplication compartment is defined by portions of both the base housingand the detachable housing section.

[0046] According to a further teaching of the present invention, thebase housing section includes the displaceable applicator base, at leasta portion of the fluid delivery system, and the processing unit, and atleast a first portion of the drive system, and the detachable housingsection includes the object holding element and at least a secondportion of the drive system.

[0047] According to a further teaching of the present invention, thebase housing section includes at least one fluid delivery system.

[0048] According to a further teaching of the present invention, thedetachable housing section is disposable.

[0049] According to a further teaching of the present invention, thedrive system is configured so as to rotate the object-holding elementabout an axis perpendicular to a direction of application of the coatingapplicator.

[0050] According to a further teaching of the present invention, the atleast one object-holding element is implemented as two object-holdingelements configured so as to simultaneously support the object at twodifferent regions along a length of the object.

[0051] According to a further teaching of the present invention, the twoobject holding elements are mechanically linked so as to rotatesynchronously about a single axis, the axis being perpendicular to adirection of application of the coating applicator.

[0052] According to a further teaching of the present invention, the atleast one coating applicator includes a pressure-pulse actuateddrop-ejection system with at least one nozzle.

[0053] According to a further teaching of the present invention, the atleast one fluid delivery system is deployed in the base housing.

[0054] According to a further teaching of the present invention, the atleast one coating applicator is implemented as a plurality of coatingapplicators and the at least one fluid delivery system is implemented asa like number of fluid delivery systems, each fluid delivery systemsupplying a different fluid coating material to the coating applicatorwith which the each fluid delivery system is in fluid communication.

[0055] According to a further teaching of the present invention, thecoating applicator, and the fluid delivery system are included in aremovable subhousing, the removable sub-housing being detachablyconnected to the displaceable applicator base.

[0056] According to a further teaching of the present invention, thespatial relationship is varied along two axes, a first axis that isparallel to a direction of application of the coating applicator, and asecond axis that is perpendicular to the direction of application of thecoating applicator.

[0057] According to a further teaching of the present invention, theobject is a catheter that includes a balloon portion on which a stent isdeployed, such that the stent is a surface of the first type and theballoon is a surface of the second type.

[0058] According to a further teaching of the present invention, theprocessing unit is responsive to an indication of the relative motion soas to change operational parameters of the coating device as required.

[0059] There is also provided according to the teachings of the presentinvention, a coating method for selectively applying a coating tosurfaces of an object, the method applying the coating based uponoptical properties of the surfaces such that the coating is applied tosurfaces of a first type and is not applied to surfaces of a secondtype, the first type of surface being optically distinguishable from thesecond type of surface, the coating device comprising: generatingrelative movement between the object and at least one optical scanningdevice and at least one coating applicator; optically scanning at leasta portion of the object by use of the at least one optical scanningdevice so as to produce output indicative of the different types ofsurfaces of the object; responding to the output by selectivelyactivating the coating applicator, thereby applying the coatingsubstantially only to surfaces of the first type.

[0060] According to a further teaching of the present invention, therelative movement includes rotating the object about an axisperpendicular to a direction of application of the coating applicator.

[0061] According to a further teaching of the present invention, thereis also provided simultaneously supporting the object at two differentregions along a length of the object.

[0062] According to a further teaching of the present invention, theselective activation includes selectively activating a pressure-pulseactuated drop ejection system with at least one nozzle.

[0063] According to a further teaching of the present invention, theselective activation includes selectively activating a pressure-pulseactuated drop ejection system with at least one nozzle that is includedin a removable sub housing, the removable sub-housing further includinga fluid delivery system in fluid communication so as to supply coatingmaterial to the coating applicator.

[0064] According to a further teaching of the present invention, theapplying is preformed by selectively activating one of a plurality ofcoating applicators, wherein the at least one coating applicatorimplemented as the plurality of coating applicators, each of theplurality of coating applicators applying a different coating.

[0065] According to a further teaching of the present invention, theapplying is preformed by selectively activating, in sequence, theplurality of coating applicators, thereby applying a plurality oflayered coats, each one of the plurality of layered coats being of acoating material that is different from adjacent layered coats.

[0066] According to a further teaching of the present invention,responding to the output includes the output being indicative of aballoon portion of catheter and a stent deployed on the balloon, suchthat the stent is a surface of the first type and the balloon is asurface of the second type.

[0067] According to a further teaching of the present invention,responding to the output includes the output being indicative only of asurface of the first type thereby applying the coating to substantiallythe entire surface of the object.

[0068] According to a further teaching of the present invention, thereis also provided varying a spatial relationship between the coatingapplicator and the object.

[0069] According to a further teaching of the present invention, thevarying is along two axes, a first axis that is parallel to a directionof application of the coating applicator, and a second axis that isperpendicular to the direction of application of the coating applicator.

[0070] According to a further teaching of the present invention, thevarying is accomplished by displacing the coating applicator.

[0071] According to a further teaching of the present invention, thevarying is accomplished by varying the spatial relationship between theobject and a displaceable applicator base upon which the at least onecoating applicator and the at least one optical scanning device aredeployed.

[0072] According to a further teaching of the present invention,controlling the varying is accomplished by the processing unit.

[0073] According to a further teaching of the present invention, thereis also provided responding to an indication of the relative motion soas to change operational parameters of the coating device as required.

[0074] According to a further teaching of the present invention,generating relative movement, the optically scanning at least a portionof the object, and the selectively activating the coating are preformedwithin a housing.

[0075] According to a further teaching of the present invention, thereare multiple applicators provided for coating injection to achievebetter performance.

[0076] According to a further teaching of the present invention, thereis a cleaning material container provided to clean the applicator at theend of the application process. The cleaning material is compatible withthe drug being used.

[0077] According to a further teaching of the present invention, thereis a cover provided on the front surface of the applicator at the end ofthe use.

[0078] According to a further teaching of the present invention, a wiperis provided to clean the applicator surface.

[0079] According to a further teaching of the present invention, ametering gauge is provided to measure the quantity of coating materialapplied through the applicator.

[0080] According to a further teaching of the present invention, opticalscanning is provided by the use of a light source that can scanintensity in white, black or other colors.

[0081] According to a further teaching of the present invention, otherapplication, dispensing, and depositing methods can be used with thefeatures of the present invention.

[0082] According to a further teaching of the present invention, amethod for coating comprises (a) providing a prosthesis havingidentifiable features; (b) pre-scanning the prosthesis prior to coatingto identify the features and to obtain coating coordinates for thefeatures; and (c) depositing a coating material at desired regions ofthe prosthesis as a function of the coordinates.

[0083] According to a further teaching of the present invention, themethod comprises (d) determining paths between the coating coordinatesfor an applicator to deposit the coating material.

[0084] According to a further teaching of the present invention, themethod comprises (e) determining a sequence for the coating coordinates.

[0085] According to a further teaching of the present invention, themethod comprises (f) determining vectors between the coating coordinatesin the sequence.

[0086] According to a further teaching of the present invention, themethod comprises (d) determining a predetermined path independent of thecoating coordinates.

[0087] According to a further teaching of the present invention, thepredetermined path covers a surface area of the prosthesis, wherein thesurface area comprises the coating coordinates.

[0088] According to a further teaching of the present invention, thepredetermined path is a function of the overall contour or geometricshape of the prosthesis.

[0089] According to a further teaching of the present invention, themethod comprises (d) post-scanning the prosthesis after coating.

[0090] According to a further teaching of the present invention, thepost-scanning comprises rotating the prosthesis and detecting of thecoated prosthesis.

[0091] According to a further teaching of the present invention, thepre-scanning comprises rotating the prosthesis and detecting of theprosthesis.

[0092] According to a further teaching of the present invention,detecting comprises detecting energy from the identifiable features ofthe prosthesis.

[0093] According to a further teaching of the present invention, thepre-scanning comprises analyzing the images for edges associated withthe prosthesis.

[0094] According to a further teaching of the present invention, thepre-scanning comprises determining the coating coordinates from theedges.

[0095] According to a further teaching of the present invention,detecting comprises capturing energy transmitted around identifiablefeatures of the prosthesis.

[0096] According to a further teaching of the present invention,pre-scanning comprises analyzing images for the edges associated withthe prosthesis.

[0097] According to a further teaching of the present invention,pre-scanning comprises determining the coating coordinates from theedges.

[0098] According to a further teaching of the present invention, thecoating material is chosen from polymers, therapeutic agents, andmixtures thereof.

[0099] According to a further teaching of the present invention, themethod for coating comprises (a) providing a prosthesis; (b)pre-scanning the prosthesis prior to coating to obtain coatingcoordinates for the prosthesis; (c) coating the prosthesis at thecoating coordinates; and (d) post-scanning the prosthesis after coating.

[0100] According to a further teaching of the present invention, thecoating comprises translating the coating applicator and drop-on-demanddelivery of a quantity of coating from a coating applicator, whereinsaid translating and said delivery are on-the-fly.

[0101] According to a further teaching of the present invention, thecoating process comprises raster type coating step.

[0102] According to a further teaching of the present invention, thecoating process comprises vector type coating step.

[0103] According to a further teaching of the present invention,pre-scanning comprises rotating the prosthesis and detecting of theprosthesis.

[0104] According to a further teaching of the present invention,pre-scanning comprises rotating a detector and detecting of theprosthesis.

[0105] According to a further teaching of the present invention,post-scanning comprises rotating the prosthesis and detecting of thecoated prosthesis.

[0106] According to a further teaching of the present invention,post-scanning comprises rotating a detector and detecting of the coatedprosthesis.

[0107] According to a further teaching of the present invention,detecting comprises capturing energy from the prosthesis or capturingenergy transmitted around the prosthesis.

[0108] According to a further teaching of the present invention,pre-scanning and the post-scanning comprises analyzing the images foredges of the prosthesis.

[0109] According to a further teaching of the present invention,pre-scanning comprises determining the coating coordinates from theedges.

[0110] According to a further teaching of the present invention, theanalyzing comprises comparing images from the pre-scanning and thepost-scanning.

[0111] According to a further teaching of the present invention,analyzing comprises identifying coating errors.

[0112] According to a further teaching of the present invention, themethod comprising repeating the coating step to re-coat the prosthesisat coordinates associated with detected coating errors.

[0113] According to a further teaching of the present invention, themethod comprises assigning a coating quality approval to the coatedprosthesis.

[0114] According to a further teaching of the present invention,analyzing comprises optically distinguishing a first type of surfacefrom a second type of surface.

[0115] According to a further teaching of the present invention,analyzing comprises rendering a three-dimensional shape from the images.

[0116] According to a further teaching of the present invention,analyzing comprises identifying pigment in a coating applied to theprosthesis.

[0117] According to a further teaching of the present invention, coatingcomprises jetting with hot air, wherein the hot air evaporates avolatile solvent in a coating material.

[0118] According to a further teaching of the present invention, coatingcomprises directing infrared radiation, wherein the infrared radiationevaporates a volatile solvent in a coating material.

[0119] According to a further teaching of the present invention, thecoating material is chosen from polymers, therapeutic agents, andmixtures thereof.

[0120] According to a further teaching of the present invention, themethod for coating comprises (a) providing a prosthesis havingidentifiable features; (b) determining a predetermined path independentof the features; and (c) coating the prosthesis at desired regions,wherein said regions are a function of the features.

[0121] According to a further teaching of the present invention, thepredetermined path covers a surface area of the prosthesis, wherein thesurface area comprises the desired regions.

[0122] According to a further teaching of the present invention, thepredetermined path is a function of the overall contour or geometricshape of the prosthesis.

[0123] According to a further teaching of the present invention, thecoating process comprises a raster type coating step.

[0124] According to a further teaching of the present invention, thecoating material is chosen from polymers, therapeutic agents, andmixtures thereof.

[0125] According to a further teaching of the present invention, theapparatus for coating comprises an applicator for applying a coatingmaterial to a prosthesis; a detector for scanning the prosthesis; and anapplicator controller connected to the detector and the applicator,wherein the applicator controller is adapted to on-the-fly coating.

[0126] According to a further teaching of the present invention, theprosthesis comprises identifiable features for which the detectorprovides coating coordinates for the applicator controller.

[0127] According to a further teaching of the present invention, theapplicator controller is adapted to determine paths between the coatingcoordinates for the applicator.

[0128] According to a further teaching of the present invention, thesystem for coating comprises (a) means for providing a prosthesis havingidentifiable features; (b) means for pre-scanning the prosthesis priorto coating to identify the features and to obtain coating coordinatesfor the features; and (c) means for applying a coating material atdesired regions of the prosthesis as a function of the coordinates.

[0129] According to a further teaching of the present invention, thesystem comprising (d) means for determining paths between the coatingcoordinates for an applicator.

[0130] According to a further teaching of the present invention, thesystem comprising (e) means for determining a sequence for the coatingcoordinates.

[0131] According to a further teaching of the present invention, thesystem comprising (f) means for determining vectors between the coatingcoordinates in the sequence.

[0132] According to a further teaching of the present invention, thesystem comprising (d) means for determining a predetermined pathindependent of the coating coordinates.

[0133] According to a further teaching of the present invention, acomputer program product for coating comprises computer-readable mediahaving computer-readable code, the computer program product comprisingthe following computer-readable program code for effecting actions in acomputing platform (a) program code for providing a prosthesis havingidentifiable features; (b) program code for pre-scanning the prosthesisprior to coating to identify the features and to obtain coatingcoordinates for the features; and (c) program code for depositing acoating material at desired regions of the prosthesis as a function ofthe coordinates.

[0134] According to a further teaching of the present invention, thecomputer program comprises (d) program code for determining pathsbetween the coating coordinates for an applicator.

[0135] According to a further teaching of the present invention, thecomputer program comprises (e) program code for determining a sequencefor the coating coordinates.

[0136] According to a further teaching of the present invention, thecomputer comprises (f) program code for determining vectors between thecoating coordinates in the sequence.

[0137] According to a further teaching of the present invention, thecomputer program product comprising (d) program code for determining apredetermined path independent of the coating coordinates.

[0138] According to a further teaching of the present invention, theapplicator control module comprises an applicator adapted todrop-on-demand a quantity of coating material at a desired location of aprosthesis; and an applicator controller adapted to on-the-fly coating.

[0139] According to a further teaching of the present invention, theapplicator controller comprises of a servo controller, a driver for saidapplicator, and a location feedback device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0140] The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein: FIG. 1 is a cut-awayside elevation of a stent coating device constructed and operativeaccording to the teachings of the present invention.

[0141]FIG. 2 is a cut-away perspective view of the stent coating deviceof FIG. 1.

[0142]FIG. 3 is a perspective detail of an alternative displaceableapplicator head constructed and operative according to the teachings ofthe present invention, shown here configure with disposable coatingapplicators.

[0143]FIG. 4 is a cut-away perspective view of the stent coating deviceof FIG. 1, showing the detachable section of the housing separated fromthe base section of the housing.

[0144]FIG. 5 is a perspective detail of an upper stent holding element,constructed and operative according to the teachings of the presentinvention.

[0145]FIG. 6 is a side elevation of the stent coating device of FIG. 1showing the full length of a catheter being supported by the supportantenna.

[0146]FIG. 7A is a flow chart of a non-limiting embodiment of a methodfor coating a stent according to the present invention.

[0147]FIG. 7B is a flow chart of the method known in the art for coatinga stent.

[0148]FIG. 8 is a flow chart of a non-limiting embodiment of thepre-coating procedure according to the present invention.

[0149]FIG. 9A is a flow chart of a non-limiting embodiment of thecoating procedure according to the present invention.

[0150]FIG. 9B is a flow chart of a procedure for coating a stent using apre-selected library.

[0151]FIG. 9C is a flow chart of a procedure for coating a stent usingreal-time imaging.

[0152]FIG. 10 is a flow chart of a non-limiting embodiment of thepost-coating procedure according to the present invention.

[0153]FIG. 11 illustrates a detail of a stent on a balloon catheter, anda blowup perspective of the stent surface to be coated.

[0154]FIG. 12 illustrates a flow chart of a non-limiting embodiment ofraster coating without the use of pre-scanning or post-scanning.

[0155]FIG. 13 illustrates a flow chart of an embodiment of “on-the-fly”translation of the applicator and delivery of the coating material. Inalternative embodiments, the servo controller 705, Z drive 710, and Zlocation feedback device 715 can be all be bundled into the applicationcontroller 720.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0156] The present invention is a method and device, which is suitablefor use in an operating theater just prior to implantation, forselectively applying a medical coating to an implantable medical device,for example a stent.

[0157] The principles and operation of a coating device according to thepresent invention may be better understood with reference to thedrawings and the accompanying description.

[0158] By way of introduction, the embodiment discussed herein is adevice for applying a medical coating to a stent deployed on a catheter,the coating being applied just prior to implantation and if desired inthe operating theater. The use of optical scanning devices enables aprocessing unit to distinguish between the surface area of the stent andthe surface area of the catheter. The processing unit selectivelyactivates the coating applicator so as to apply the coating tosubstantially only the stent and not the balloon or other portion of thecatheter. The coating applicator discussed herein is, by non-limitingexample, a pressure-pulse actuated drop-ejection system with at leastone nozzle. A readily available pressure-pulse actuated drop-ejectionsystem, which is well suited for the present invention, is adrop-on-demand inkjet system. It should be noted, however, that anycoating application system that may be selectively activated is withinthe intentions of the present invention. While the discussion herein isspecific to this embodiment, which is intended for use in an operatingtheater, among other places, this embodiment it is intended as anon-limiting example of the principals of the present invention. It willbe readily apparent to one skilled in the art, the range of applicationssuited to the principals of the present invention. Even the devicedescribed herein, as a non-limiting example, with minor adaptations tothe object-holding element and choice of fluid coating materials, iswell suited for a wide range of objects to which a coating is applied.

[0159] Referring now to the drawings, as mentioned above, FIG. 1illustrates a device for applying a coating to a stent 2 that isdeployed on a catheter 4. The coating being applied may be a syntheticor biological, active or inactive agent. The perspective view of FIG. 2is of the same side of the device as FIG. 1, and therefore when thedescription of elements of the device will be better understood, FIG. 2will be referenced. The catheter 4 is placed in an applicationcompartment 40 and held in position by a rotatable catheter-holding base6 and a rotatable upper catheter-holding element 8, which are configuredfor substantially continued rotation, that is they may complete aplurality of full 360 degree rotations, as required, during the coatingprocess. The actual rotation may be substantially fully continuous(non-stop) or intermittent. The upper catheter-holding element will bediscussed in detail below with regard to FIG. 4. The enclosedapplication compartment provides a sterile environment in which thecoating process is performed. The rotation of the catheter-holding baseand the upper catheter-holding element is actuated and synchronized by amotor and gear system that includes gear clusters 12, 14, 16, and shaft18 (see also FIG. 2). Alternatively, the gears may be replaced by drivebelts or drive chains. The remaining length of the catheter is supportedby a support antenna 22, as illustrated, by non-limiting example, inFIG. 6. As noted above, the object-holding elements may be modified soas to hold any object suitable for coating according to the teachings ofthe present invention.

[0160] The coating is applied by a drop-on-demand inkjet system inassociation with an optical scanning device and processing unit. As theobject is rotated by the object-holding element, the optical scanningdevice scans the surface of the object. The out-put from the scanningdevice is used by the processing unit to determine if the surface areacurrently aligned with the coating applicator is of the type of surfaceto be coated. When it is determined that the desired type of surface isaligned with the coating applicator, the processing unit activates thecoating applicator and the coating is dispensed. The embodiment shownhere includes three inkjet coating applicators 30 a, 30 b, and 30 c, andtwo optical scanning devices 32 a and 32 b. The optical scanning devicesmay be configured to generate digital output or an analog signal, whichis in turn analyzed by the processing unit. It should be noted that thenumber of coating applicators and scanning devices may be varied to meetdesign or application requirements. The three coating applicators andthe two optical scanning devices are mounted on a displaceableapplicator head 34. The position of the applicator head within theapplication compartment, and thereby the spatial relationship betweenthe coating applicator and the stent, or other object being coated, isregulated by the application control module 36, which is, in turn,controlled by the processing unit. The change of position of theapplicator head is effected vertically by turning the verticalpositioning screw 60 in conjunction with guide shaft 62, and thehorizontally by turning the horizontal positioning screw 64 inconjunction with guide shaft 66. The vertical repositioning inconjunction with the rotation of the object enables the coatingapplicator to traverse substantially the entire surface of the objectrequiring coating.

[0161] Fluid coating material is stored in three fluid reservoirs 50 a,50 b, and 50 c (see FIG. 2), and supplied to the respective coatingapplicators by the fluid supply hoses 52 a, 52 b and 52 c (see FIG. 2).In general use, each of the fluid reservoirs contains a differentcoating material, thus, each coating applicator will deposit a differentcoating material on the stent or other objected being coated, asrequired. Further, a plurality of coats may be applied, each coat beingof a different coating material and, if required, of a differentthickness. Thus, at the time of coating, a single appropriate coatingmaterial may be chosen from the materials provides, or a combination ofcoatings may be chosen. It should be noted that while the fluidreservoirs are shown here in a compartment inside the device housing,this need not always be the case, and the reservoirs may be external tothe housing.

[0162] It should be noted that, alternatively, the inkjet system may bedeployed in a disposable housing that also includes a fluid reservoirfilled with coating material. The fluid reservoir may be an enclosedvolume that is integral to the disposable housing or it may be a coatingfilled cartridge that is inserted into a receiving cavity in thedisposable housing. In this case, as illustrated in FIG. 3, thedisplaceable applicator head 34 is configured so as to accept one ormore of the disposable housings 36 a, 36 b, and 36 c, which in turnhouse inkjet coating applicators 38 a, 38 b, and 38 e respectively. Thefluid reservoirs (not shown) for each applicator are housed in thatportion of the disposable housing that is deployed within thedisplaceable applicator head 34.

[0163]FIG. 4 illustrates how the base housing section 70 and thedetachable housing section 72 are interconnected. The two sections areheld together by inserting pins 74, extending from the detachablehousing section, into the corresponding holes 76, located in the basehousing section, and engaging the latch mechanism 78 with the catchelement 80. Detachment of the two sections is accomplished by pressingthe release “button” 84, which raises the end 82 of the latch therebyreleasing the catch element. The two sections are then pulled apart. Asseen here more clearly, the application compartment is defined by a top,floor and three walls located in the detachable housing section and onewall on the base housing section. The detachable housing section isconfigured so as to be disposable, or if desired, easily cleaned andre-sterilized.

[0164] The detail of FIG. 5 shows the components of the uppercatheter-holding element. Extending from substantially the center of therotating base plate 90, is a threaded tube 92. This tube is the externalend of the passageway through which the catheter tip with the stentattached is inserted in order to deploy the stent in the applicationcompartment of the coating device. The tube is cut longitudinallyseveral times, to create threaded sections 98, here six, that areconfigured so as to flex outward from the center. The tightening-disk94, has a correspondingly threaded center hole for deployment on thetube 92 such that when the tightening-disk is brought to a positionproximal to the base plate, the threaded sections near the end of thetube will flex outwardly thereby enlarging the diameter of the opening.The gripping element 96 also has divergently flexing “fingers” 100. Inoperation, the gripping element is deployed around the catheter, whichis then passed through the tube and into the application compartment.Once the catheter is positioned on the catheter holding base, thegripping element is at least partially inserted into the opening of thetube. The tightening-disk 94 is then rotated about the tube, and therebybrought to a position proximal to the end of the tube, the outwardlyflexing sections of the tube 98 are brought into an un-flexed statethereby decreasing the diameter of the opening. The decrease in thediameter of the tube opening pushes the “fingers” of the grippingelement against the catheter, thereby holding the catheter in place.

[0165] A non-limiting example of the stent coating process asaccomplished by the above describe device would be as follows:

[0166] 1. The fluid reservoirs are filled with the required fluidcoating materials.

[0167] 2. The parameters of the coating are inputted into the processingunit. The parameters may include, by non-limiting example, the coatingmaterial to be applied, the thickness of the coating, number of multiplelayers of different coating material, the order in which the layeredmaterials are to be applied, and the thickness of each layer. Theparameters may be determined by the physician at the time the coating isapplied or the parameters may be pre-set, such as those determined bymedical regulations. In the case of pre-set parameters, the physicianwould simply input a “start” command.

[0168] 3. The catheter is positioned in the application compartment andthe upper catheter-holding element is tightened.

[0169] 4. As the catheter rotates, the optical scanning device scans thesurface of the catheter, to distinguish between the surface of theballoon and the surface of the stent.

[0170] 5. When a portion of the surface of the stent is detected anddetermined to be in alignment with the appropriate coating applicator,the processing unit selectively activates the applicator, therebyejecting the necessary amount of coating material, which is depositedsubstantially only on the surface of the stent.

[0171] 6. Throughout the coating process, the position of the applicatorhead is adjusted as required. This adjustment may bring the coatingapplicator closer to, or farther away from, the surface of the stent,and it may adjust the vertical deployment of the coating applicator,thereby allowing different areas of the surface of the stent to becoated. Further, if a different fluid coating material is needed for adifferent layer of the coating, the coating applicator for thatparticular coating material may be brought into appropriate alignmentfor deposition of the new coating material on the stent.

[0172] 7. When the coating process is completed, the catheter with thenow coated stent is removed from the device, and the stent is ready forimplantation.

[0173] 8. The detachable housing section is removed and may be cleanedand sterilized for re-use, or simply discarded.

[0174] It should be noted that in some cases it may be desirable to coatsubstantially the entire surface of the object being coated. This may beaccomplish in at least two ways. The object itself may have only onetype of surface. Alternatively, the scanning device may be configured soas to provide adjustable scanning sensitivity. In such a case, thesensitivity of the scanning device may be adjusted such that the out-putis indicative of only one type of surface and the processing unit isunable to distinguish between different types of surfaces.

[0175] The flowchart of FIG. 7A illustrates a process for coating aprosthesis 102 based on the present invention. In this non-limitingexample, the prosthesis is a stent that is to be coated with atherapeutic agent. The first step 105 is to place the stent andtherapeutic agent container in the stent coating device. The system isthen ready for processing the stent. The system starts at 110. Thepre-coating procedure 115 collects information in the processing unit(not shown) of the stent coating device to be used during the coatingprocedure 120. The post-coating procedure 125 verifies that the stenthas been properly coated and should be approved for removal 130. Theflowchart of FIG. 7B illustrates the process for coating stents 140known in the art. The user selects a pattern 145 according to the typeof stent to be coated and the pattern of coating to be delivered. Thepattern selected varies on parameters provided by the stent manufacturerand the coating to be applied. The process starts 150 according to thepattern that has been selected. The coating procedure 155 applied thecoating to the stent, and once complete, the coated stent 160 is readyfor removal.

[0176]FIG. 8 illustrates the pre-scanning procedure 115. The stent ispre-scanned 205 prior to the coating procedure 120. In parallel, theapplication control module is initialized 200. Initialization of theapplication control module comprises finding a specific point on thestent to begin coating. The pre-scan is analyzed 210 in the processingunit. The analysis determines and compiles the coating coordinates table215 to be used to position the application control module.

[0177] There is a large standard deviation between stents of the samedesign, especially after the stent is crimped on the balloon catheter.The preprogrammed pattern is not helpful to manage these deviations fromthe design. Pre-scanning can provide a check for defects in the stentstructure prior to coating. Pre-scanning can also provide the bestpositions on to which to spray the coating. Crimping does not alwaysresult in a uniform deformation of the stent structure. Some portions ofthe stent may be more densely packed than other portions. Someintersections of stent struts may have different angles of incidence.Pre-scanning can provide the optimal path to follow over the stentsurface to be coated. Some applications require only a portion of thestent to be coated. Pre-scanning can prevent over-jetting of the coatingon a specific location. Over-jetting can result in inadvertent coatingfrom the stent on the balloon catheter.

[0178] Scanning can be achieved by a variety of imaging techniques knownin the art of imaging, including but not limited to photographic, video,infrared, and VCSEL (Vertical Cavity Surface Emitting Laser)technologies using a variety of detectors. VCSELs can be used as thedetector for optical imaging, and can double as the applicator itself.Choquette, Kent D., Vertical Cavity Surface Emitting Lasers—Light forInformation Age, MRS Bulletin, pp. 507-511, July 2002. In onenon-limiting embodiment, a photograph of the stent is taken by adetector. The stent is rotated slightly (e.g., one-half to a fewdegrees) and then another photograph is taken, resulting in at leastseveral dozen photographs total. The detector is focused sufficientlyclose to the stent to record enough resolution relative to the coatingdroplet to be applied. If the stent is long, the rotation may have to berepeated to capture the top and bottom of the stent.

[0179] A light source can be positioned on the same side as the detectoror on the opposite side of the detector relative to the stent. In theembodiment where the light source is on the same side as the detector,the detector received light reflected by the stent. The stent appearslight in color and the balloon appears dark in color. In the embodimentwhere the light source is on the opposite side of the detector, thedetector receives light transmitted through the balloon and around thestent struts. The stent appears dark in color and the balloon appearslight in color. The contrast between the light and dark color in bothembodiments can be used for edge analysis. Edge analysis comprisesdetermining the edges of the stent and finding the center-line of stentsurface to be coated. The edges and center-line determine the coatingcoordinates which are collected for each surface of the stent to becoated in the coating coordinates table.

[0180] In one non-limiting embodiment, the pre-scan is compared to anindex of patterns in the processing unit. This can be used to confirmthe accuracy of the edge analysis and provide a safety measure fordetection of defects in the stent or errors in the edge analysis.

[0181] Coating coordinates can be interpreted and coded as raster orvector type of data forms. These data forms describe differenttranslation of the applicator by the Z driver. Both data forms compriseusing an algorithm to find all the coordinates of the stent that shouldbe coated and compiling a map of “to be coated points” or coordinates.Chart 1 illustrates a map of coordinates showing the point location onZ, as a function of the relative axial rotation in degrees.

[0182] Vector type coating comprises taking the unique variables (e.g.,Z and rotation), and using another algorithm to select the shortestdistance or otherwise most efficient path to move between one coatingcoordinate and the next most proximate coordinate to be coated. Vectorcoating can also comprise creating a list of coordinates in sequentialorder. Table 1 illustrates a “best pass algorithm” as a coordinate tablecorrelating location on Z to angle of rotation for each coordinate.TABLE 1 Coordinate no. Z Rotation 1 3 15 2 6 30 3 9 45 4 6 60 5 9 60 615 60

[0183] Control software in the processing unit can calculate a set ofmovement vectors for the application control module between each set ofsequential coordinates. Vector parameters may comprise coordinates, Δz(change in location between two adjacent points or coordinates on Zaxis), Δrot (change in angle between coordinates), velocity between thecoordinates, etc. Table 2 illustrates vectors that can be calculatedfrom coordinate table in Table 1. Each vector can have a differentvelocity associated with it represented as values a, b, and c. Eachvector can have a difference quantity associated with it represented asvalues d, e, f, g, h which may be the same of different. Otherparameters can also be associated with each vector. TABLE 2 Vector ΔzΔrot Velocity Quantity 1-2 3 15 a d 2-3 3 15 a e 3-4 −3 15 a f 4-5 3 0 bg 5-6 6 0 c h

[0184] A raster type coating comprises using an algorithm to find allthe coordinates of the stent that should be coated and compiling a mapof coordinates. This is similar to vector type coating as is illustratedin Chart 1 above. Raster type coating, however, also comprises takingthe unique variables (e.g., Z and rotation), and using a differentalgorithm to calculate and compile a coordinate table of Z coordinatesfor each rotation angle in predetermined increments of rotation. Theterm “rotation resolution” refers to the number of increments inrotation angle. Raster type coating is rotation-resolution-specific.This means that raster printing is calculated and executed at onespecific rotation resolution, or in a variety of other manipulationsinter-relating the prosthetic item to be coated, the holder for suchprosthetic and the applicator nozzle. Table 3 illustrates a coordinatetable correlating angle of rotation with locations on Z. Theselocations: Z1, Z2, Z3, Z4, etc. represent intersections with the surfaceof the stent to be coated at each angle of rotation. TABLE 3 ROTATIONANGLE Z1 Z2 Z3 Z4 15 3 9 30 6 20 45 9 60 6 9 15

[0185] Control software in the processing unit can calculate the Zcoordinates for each angular position and direct the application controlmodule and coating applicator to go to an angular rotation position andmove along Z at a regulated, constant or variable velocity. While movingalong Z, the coating applicator injects at Z1, Z2, Z3, Z4, etc. Aftertraveling the full length of the stent along Z, the application controlmodule moves the coating applicator to the next angle of rotation,changes the direction along Z (now opposite the previous direction)which the coating applicator travels. While traveling in this newdirection, the coating applicator injects over the next Z locations.

[0186] Additional raster-based manipulations could include, for example,rotational movements of the stent in conjunction with serial, steppedZ-axis movements, or “screw-like” movements along a helical path of thestent accomplished by simultaneous movement of rotation and steppedZ-axis movements as is described below. In any event, the raster-basedcoating process results in motion with respect to the stent andapplicator which covers the entire prosthetic, while the vector-basedcoating process only travels over the “to be coated” surfaces.Consequently, the vector-based approach is object dependent, while theraster-based approach is simply system defined.

[0187]FIG. 11 illustrates a stent 2 on a balloon catheter 4. The axis ofrotation, Z, is also the axis of symmetry 500 for the stent. Themagnified window of FIG. 11 shows the stent structure to be coated 505and gaps in stent structure where balloon catheter 4 is not covered bythe stent. During scanning, the stent is rotated in incremental anglesaccording to the rotation resolution to generate the coordinate table.During coating, the application control module rotates the stent in thesame incremental angles and positions the coating applicator at the Zlocations to coat the stent. In one non-limiting embodiment, the coatingapplicator can drop-on-demand a coating with accuracy as is known in theart of ink-jet printing.

[0188] The flowchart of FIG. 9A illustrates an embodiment of the coatingprocedure 120. The present embodiment contemplates raster coatingaccomplished by longitudinal movement of the applicator along the lengthof a cylindrical body and point-to-point (“PTP”) rotation of thecylindrical body or applicator around the circumference of thecylindrical body. An initial angle of rotation is selected 300. Theapplication control module moves the coating along the Z axis 310, whilecontrolling drop-on-demand at Z coordinate 315, and receiving the nextcoating coordinate from the processing unit 305. Once the coatingapplicator has moved along the length of the stent, the applicationcontrol module changes the direction of travel along the Z axis of thecoating applicator 320, and rotates the stent to the next angle ofrotation 325. This process is repeated by repeating steps 310-325 untilthe stent has been coated according to the coordinate table. In onenon-limiting embodiment, the change in incremental angle of rotation canbe one-half of one degree and can require up to 500 rotations of thestent to coat each point in the coordinate table. Multiple coatings canbe applied sequentially or simultaneously by repeating the steps and/orchanging the coating reservoir.

[0189] In another embodiment, raster coating can be accomplished bycoating along the circumferential rotation of the cylindrical body orapplicator with PTP longitudinal movement of the applicator along thelength of the cylindrical body. In another embodiment, raster coatingcan be accomplished by both circumferential rotation of the cylindricalbody or applicator and longitudinal movement of the applicator with PTPlongitudinal movement of the applicator or PTP rotation of thecylindrical body or applicator along the circumference of thecylindrical body. This embodiment results in a spiral or “screw”predetermined path.

[0190] In other embodiments, raster coating can be accomplished byfollowing a predetermined path to apply coating material at desiredlocations of the prosthesis without regard to the pattern of thecoating. In some embodiments, this predetermined path can incorporatethe overall contour or geometrical shape of the prosthesis toefficiently cover the surface area which includes the desired locationsto be coated. In some certain embodiments, efficiency can be realized byutilizing axes of symmetry or other geometrical simplifications of theoverall contour of the prosthesis.

[0191] The flowchart of FIG. 9B illustrates the coating procedure 155which is known in the art. The coating nozzle is in an initial position330. The controller receives coordinates from a user selected pattern335. The controller interprets the coordinates into X, Y, and Z constantvelocity movement 340, and positions the nozzle to jet by controllingthe nozzle delivery 350, the nozzle motion 355, and/or the stent motion360. The nozzle then drop-on-demand 365. Then the nozzle travels overthe stent to the next coordinate based on the user selected patter.

[0192] The flowchart of FIG. 9C illustrates the coating procedure 155which is known in the art also begins with the coating nozzle at aninitial position 330. A picture of the nozzle, stent, and/or coating istaken 342. The picture is analyzed using vision software 345. Thecontroller interprets the picture and positions the nozzle to jet bycontrolling the nozzle delivery 350, the nozzle motion 355, and/or thestent motion 360. The nozzle then drop-on-demand 365. This requiresreal-time imaging and adjustment prior to coating portions of the stent.

[0193] The flowchart in FIG. 10 illustrates an embodiment of the presentinvention including a post-coating procedure 125. The coating applicatoris held in stand-by mode 400, while the stent is post-scanned 405, scananalysis 410 analyzes the coated stent for mistakes in coating andprovides coating quality assurance and approval 420. If approved, thestent coating is complete 130. In one non-limiting embodiment, thecoating comprises pigment to facilitate scan analysis by differentiatingbetween the stent and coating. In one non-limiting embodiment, thepre-scan images can be used for the approval of the stent. Post-scanningfacilitates locating coordinates where coating was not applied becauseof jetting problems. Post-scanning also facilitates in locating leakageor “overspray” points where the coating has leaked from the stent ontothe balloon catheter.

[0194] The flow chart in FIG. 12 illustrates an embodiment of rastercoating without pre-scanning or post-scanning. The method for coating aprosthesis 600, begins with setting 605 the predetermined length L,incremental linear movement Δx, and incremental angular movement Δθ,along with a reference point recognized as a characteristic feature ofthe prosthesis. The detector is turned on 610. The detector andapplicator move 615 linearly from the reference point an incrementaldistance Δx and Δθ along L. The detector looks for targets 620 asdesired locations on the prosthesis to be coated. If the detector findsa target, the applicator drop-on-demand 625. If the detector does notfind a target or after the applicator drop-on-demand 625, the detectorand applicator move Δx 630. The detector determines whether it hastraveled the full L of the prosthesis 635 by determining whether the sumof the Δx movements is greater than or equal to L (ΣΔx≧L). If thedetector has not traveled the full L, then the detector and applicatormove Δx 640 and look for a target 620. If the detector has traveled thefull L, then the detector and applicator move Δθ 645. The detectordetermined whether it has traveled around the entire contour of theprosthesis 650 by determining whether the sum of the Δθ movements isgreater than or equal to 360 degrees (ΣΔθ≧360°). If the detector has nottraveled 360 degrees, then the detector and applicator move 615 linearlyan incremental distance Δx and Δθ along L. If the detector has traveled360 degrees, then the coating is finished 655.

[0195] The present invention teaches a method for coating a prosthesisas well as an apparatus for coating a prosthesis, a system for coating aprosthesis, and an application control module for coating a prosthesis.

[0196] It will be appreciated that the above descriptions are intendedonly to serve as examples, and that many other embodiments are possiblewithin the spirit and the scope of the present invention.

What is claimed is:
 1. A method for coating comprising: (a) providing aprosthesis having identifiable features; (b) pre-scanning saidprosthesis prior to coating to identify said features and to obtaincoating coordinates for said features; and (c) applying a coatingmaterial at desired regions of the prosthesis as a function of saidcoordinates.
 2. A method according to claim 1, further comprising: (d)determining paths between said coating coordinates for an applicator todeposit said coating material.
 3. A method according to claim 2, furthercomprising: (e) determining a sequence for said coating coordinates. 4.A method according to claim 3, further comprising: (f) determiningvectors between the coating coordinates in said sequence.
 5. A methodaccording to claim 1, further comprising: (d) determining apredetermined path independent of said coating coordinates.
 6. A methodaccording to claim 5, wherein said predetermined path covers a surfacearea of said prosthesis, wherein said surface area comprises saidcoating coordinates.
 7. A method according to claim 6, wherein saidpredetermined path is a function of the overall contour or geometricshape of said prosthesis.
 8. A method according to claim 1, furthercomprising: (d) post-scanning said prosthesis after coating.
 9. A methodaccording to claim 8, wherein said post-scanning comprises rotating saidprosthesis and detecting of said coated prosthesis.
 10. A methodaccording to claim 1, wherein said pre-scanning comprises rotating saidprosthesis and detecting of said prosthesis.
 11. A method according toclaim 10, wherein said detecting comprises detecting energy from saididentifiable features of said prosthesis.
 12. A method according toclaim 11, wherein said pre-scanning further comprises analyzing saidimages for edges associated with said prosthesis.
 13. A method accordingto claim 10, wherein said pre-scanning further comprises determiningsaid coating coordinates from said edges.
 14. A method according toclaim 10, wherein said detecting comprises capturing energy transmittedaround identifiable features of said prosthesis.
 15. A method accordingto claims 14, wherein said pre-scanning further comprises analyzing saidimages for the edges associated with said prosthesis.
 16. A methodaccording to claim 15, wherein said pre-scanning further comprisesdetermining said coating coordinates from said edges.
 17. A methodaccording to claim 1, wherein said coating material is chosen frompolymers, therapeutic agents, and mixtures thereof.
 18. A method forcoating comprising: (a) providing a prosthesis; (b) pre-scanning saidprosthesis prior to coating to obtain coating coordinates for saidprosthesis; (c) applying a coating material to said prosthesis at saidcoating coordinates; and (d) post-scanning said prosthesis aftercoating.
 19. A method according to claim 18, wherein said applyingcomprises translating an applicator and delivering drop-on-demand of aquantity of coating from said coating applicator, wherein saidtranslating and said delivering are on-the-fly.
 20. A method accordingto claim 18, wherein said applying comprises raster type coating.
 21. Amethod according to claim 18, wherein said applying comprises vectortype coating.
 22. A method according to claim 18, wherein saidpre-scanning comprises rotating said prosthesis and detecting of saidprosthesis.
 23. A method according to claim 18, wherein saidpre-scanning comprises rotating a detector and detecting of saidprosthesis.
 24. A method according to claim 18, wherein saidpost-scanning comprises rotating said prosthesis and detecting of saidcoated prosthesis.
 25. A method according to claim 18, wherein saidpost-scanning comprises rotating a detector and detecting of said coatedprosthesis.
 26. A method according to claim 22, wherein said detectingcomprises capturing energy from said prosthesis or capturing energytransmitted around said prosthesis.
 27. A method according to claim 22,wherein said pre-scanning and said post-scanning further comprisesanalyzing said images for edges of said prosthesis.
 28. A methodaccording to claim 27, wherein said pre-scanning further comprisesdetermining said coating coordinates from said edges.
 29. A methodaccording to claim 22, wherein said analyzing comprises comparing imagesfrom said pre-scanning and said post-scanning.
 30. A method according toclaim 29, wherein said analyzing further comprises identifying coatingerrors.
 31. A method according to claim 30, further comprising repeatingsaid coating to re-coat said prosthesis at coordinates associated withdetected coating errors.
 32. A method according to claim 30, furthercomprising assigning a coating quality approval to said coatedprosthesis.
 33. A method according to claim 22, wherein said analyzingcomprises optically distinguishing a first type of surface from a secondtype of surface.
 34. A method according to claim 33, wherein saidanalyzing further comprises rendering a three-dimensional shape fromsaid images.
 35. A method according to claim 22, wherein said analyzingcomprises identifying pigment in a coating applied to said prosthesis.36. A method according to claim 18, wherein said coating comprisesjetting with hot air, wherein said hot air evaporates a volatile solventin a coating material.
 37. A method according to claim 18, wherein saidcoating comprises directing infrared radiation, wherein said infraredradiation evaporates a volatile solvent in a coating material.
 38. Amethod according to claim 18, wherein said coating material is chosenfrom polymers, therapeutic agents, and mixtures thereof.
 39. A methodfor coating comprising: (a) providing a prosthesis having identifiablefeatures; (b) determining a predetermined path independent of saidfeatures; and (c) applying a coating material to the prosthesis atdesired regions, wherein said regions are a function of said features.40. A method according to claim 39, wherein said predetermined pathcovers a surface area of said prosthesis, wherein said surface areacomprises said desired regions.
 41. A method according to claim 40,wherein said predetermined path is a function of the overall contour orgeometric shape of said prosthesis.
 42. A method according to claim 40,wherein said applying comprises raster type coating.
 43. A methodaccording to claim 39, wherein said coating material is chosen frompolymers, therapeutic agents, and mixtures thereof.
 44. An apparatus forcoating comprising: an applicator for applying a coating material to aprosthesis; a detector for scanning said prosthesis; and an applicatorcontroller connected to said detector and said applicator, wherein saidapplicator controller is adapted to on-the-fly coating.
 45. An apparatusaccording to claim 44, wherein said prosthesis comprises identifiablefeatures for which said detector provides coating coordinates for saidapplicator controller.
 46. An apparatus according to claim 45, whereinsaid applicator controller is adapted to determine paths between saidcoating coordinates for said applicator.
 47. A system for coatingcomprising: (a) providing a prosthesis having identifiable features; (b)means for pre-scanning said prosthesis prior to coating to identify saidfeatures and to obtain coating coordinates for said features; and (c)means for applying a coating material at desired regions of theprosthesis as a function of said coordinates.
 48. A system according toclaim 47, further comprising: (d) means for determining paths betweensaid coating coordinates for an applicator.
 49. A system according toclaim 48, further comprising: (e) means for determining a sequence forsaid coating coordinates.
 50. A system according to claim 49, furthercomprising: (f) means for determining vectors between the coatingcoordinates in said sequence.
 51. A system according to claim 47,further comprising: (d) means for determining a predetermined pathindependent of said coating coordinates.
 52. A computer program productfor coating, the computer program product comprising computer-readablemedia having computer-readable code, the computer program productcomprising the following computer-readable program code for effectingactions in a computing platform: (a) program code for providing aprosthesis having identifiable features; (b) program code forpre-scanning said prosthesis prior to coating to identify said featuresand to obtain coating coordinates for said features; and (c) programcode for depositing a coating material at desired regions of theprosthesis as a function of said coordinates.
 53. A computer programproduct according to claim 52, further comprising: (d) program code fordetermining paths between said coating coordinates for an applicator.54. A computer program product according to claim 53, furthercomprising: (e) program code for determining a sequence for said coatingcoordinates.
 55. A computer program product according to claim 54,further comprising: (f) program code for determining vectors between thecoating coordinates in said sequence.
 56. A computer program productaccording to claim 52, further comprising: (d) program code fordetermining a predetermined path independent of said coatingcoordinates.
 57. An applicator control module comprising: an applicatoradapted to drop-on-demand a quantity of coating material at a desiredlocation of a prosthesis; and an applicator controller adapted toon-the-fly coating.
 58. An applicator control module according to claim57, wherein said applicator controller comprises of a servo controller,a driver for said applicator, and a location feedback device.